"The closing sequence, Greenough's short film Echoes, is generally
considered to be the highlight of the film. Filmed with a camera in a
waterproof housing strapped to Greenough’s back, the sequence is
composed entirely of slow-motion footage shot inside the curl of waves,
edited to the 23-minute song "Echoes" by Pink Floyd.
The group reportedly allowed Elfick and Greenough to use the music in
their film in exchange for the use of Greenough's footage as a visual
background when they performed "Echoes" in concert."